1. Field of Invention
This invention relates to material handling systems and more particularly to a transfer device for moving a just formed good away from an injection molding machine for further processing
2. Prior Art
When injection molding machines were first put into use to make plastic goods, such goods were manually withdrawn from a mold of the machine after forming. Manual handling immediately proved to be unsatisfactory because the good was still quite hot, requiring an operator to wear heat protective clothing. Additionally, hands of the operator if caught by the mold as it closed would be readily crushed.
To overcome the problems associated with manual good removal, one solution was to place an end of a standard belt-type conveyor under the machine mold. When the mold opened after forming, mechanical means such stripper pins in the mold separated the formed good from the mold so that the good would fall onto the moving conveyor belt below. While an improvement, use of such a conveyor did not prove to be totally satisfactory. Lubricant from the mold also would fall and collect on the conveyor belt. If not removed, a good coming into contact with this lubricant could incur surface damage sufficient to impair surface quality to a degree that the good must be rejected. Good rejection was particularly likely where the good required a high quality surface finish.
Consequently, various other mechanical means have been developed to handle a good just formed in a mold or press. Examples of such means are set forth in U.S. Pat. Nos. 425,362, 3,277,521, 3,756,107 and 4,363,595. The '362 reference discloses apparatus having a pair of stripper fingers which move into an open die to dislodge a just formed part from an upper portion of the die. The dislodged part then falls onto a receiving plate located above a lower portion of the die. Next the receiving plate is withdrawn to a position clear of the die where an ejector plate pushes the part off of the receiving plate.
The assembly of the '521 reference is similar in some respects to the '362 apparatus except that it has an oscillating comb which moves into the open die to separate the culls and runners which connect the various parts during the forming from those parts. The separated parts fall onto a tray which is then withdrawn. During outward movement of the tray an outer end of the tray is guided downward to tip the tray so that the parts on the tray slide into a container. The culls and runners on the comb in turn are removed by a scrapping blade as the comb is withdrawn to fall into a further container.
The collection mechanism of the '107 reference is particularly adapted to use with a press. This mechanism may be selectively tilted so that a receiver may be reciprocated into an open die to receive a part formed therein. The receiver is carried on a slidable mount having a shaft operatively connected to a reciprocating arm which in turn in connected to a rotary drive.
The apparatus of the '595 reference has a movable loading bar assembly defined by a series of spaced apart bars. The bars are formed with longitudinal slots. The assembly may be moved into a molding machine such that parts being held on stations in the machine become positioned in the bar slots. After the stations are lowered, the assembly first moved outward and then inward again. During this further inward movement a cam follower on the assembly engages a stop block causing the assembly to tilt whereby the formed parts slide in a receptacle.